Шестакова Анна Николаевна

Resting state brain activity predicts individuals’ conformity

2013 · CHAPTER · en

MEG study of social conformity

2013 · CHAPTER · en

Automatic processing of unattended lexical information in visual oddball presentation: neurophysiological evidence

2013 · ARTICLE · en

Previous electrophysiological studies of automatic language processing revealed early (100-200 ms) reflections of access to lexical characteristics of speech signal using the so-called mismatch negativity (MMN), a negative ERP deflection elicited by infrequent irregularities in unattended repetitive auditory stimulation. In those studies, lexical processing of spoken stimuli became manifest as an enhanced ERP in response to unattended real words, as opposed to phonologically matched but meaningless pseudoword stimuli. This lexical ERP enhancement was explained by automaticactivation of word memory traces realized as distributed strongly intra-connected neuronal circuits, whose robustness guarantees memory trace activation even in the absence of attention on spoken input. Such an account would predict the automatic activation of these memory traces upon anypresentation of linguistic information, irrespective of the presentation modality. As previous lexical MMN studies exclusively used auditory stimulation, we here adapted the lexical MMN paradigm to investigate early automatic lexical effects in the visual modality. In a visual oddball sequence, matched short word and pseudoword stimuli were presented tachistoscopically in perifoveal area outside the visual focus of attention, as the subjects' attention was concentrated on a concurrent non-linguistic visual dual task in the center of the screen. Using EEG, we found a visual analogue of the lexicalERP enhancement effect, with unattended written words producing larger brain response amplitudes than matched pseudowords, starting at ~100 ms. Furthermore, we also found significant visual MMN, reported here for the first time for unattended perifoveal lexical stimuli. The data suggest earlyautomatic lexical processing of visually presented language which commences rapidly and can take place outside the focus of attention.

Fast parametric evaluation of central speech-sound processing with mismatch negativity (MMN)

2013 · ARTICLE · en

The aim of this study was to develop a paradigm for obtaining a multi-feature profile for central auditory processing of different magnitudes of prosodic and phonetic changes in speech sounds. We recorded the MMNs to three vowel identity changes, three magnitudes of changes in intensity, and vowel duration as well as to two magnitudes of pitch changes from semi-synthetic vowels in 34min. Furthermore, we examined how the type and magnitude of deviation affect the size and timing of the MMN. All sound changes elicited statistically significant MMN responses, with the MMNamplitudes increasing with an increase in sound deviance. Importantly, the MMN amplitudes for the vowel changes reflected the differences between the phonemes, as did the MMNs to vowel-duration changes reflect the categorization of these sounds to short and long vowel categories, which are meaningful in the Finnish language. This new multi-feature MMN paradigm is suitable for investigating the central auditory processing of different magnitudes of speech-sound changes and can be used, for instance, in the investigation of pre-attentive phoneme categorization. The paradigm is especially useful for studying speech and language disorders in general, language development, and evolution of phoneme categories early in life, as well as brain plasticity during native or second language learning

Electrophysiological precursors of social conformity

2013 · ARTICLE · en

Humans often change their beliefs or behavior due to the behavior or opinions of others. This study explored, with the use of human event-related potentials (ERPs), whether social conformity is based on a general performance-monitoring mechanism. We tested the hypothesis that conflicts with a normative group opinion evoke a feedback-related negativity (FRN) often associated with performance monitoring and subsequent adjustment of behavior. The experimental results show that individual judgments of facial attractiveness were adjusted in line with a normative group opinion. A mismatch between individual and group opinions triggered a frontocentral negative deflection with the maximum at 200 ms, similar to FRN. Overall, a conflict with a normative group opinion triggered a cascade of neuronal responses: from an earlier FRN response reflecting a conflict with the normative opinion to a later ERP component (peaking at 380 ms) reflecting a conforming behavioral adjustment. These results add to the growing literature on neuronal mechanisms of social influence by disentangling the conflict-monitoring signal in response to the perceived violation of social norms and the neural signal of a conforming behavioral adjustment.

Магнитоэнцефалография – новейший метод функционального картирования мозга человека

2012 · ARTICLE · ru

Статья посвящена методу магнитоэнцефалографии (МЭГ) и его применению в когнитивных исследованиях. МЭГ – одна из современных технологий нейроимиджинга. Данный метод обладает уникальными характеристиками, позволяющими с высокой точностью локализовать источники активности нейронных популяций коры головного мозга человека в пространстве и времени. Наряду с исследованиями базовых сенсорных и моторных функций мозга, МЭГ является незаменимым инструментом исследования динамики когнитивных процессов памяти, внимания, эмоций и др. Особый акцент в обзоре сделан на использовании МЭГ для изучения мозговых механизмов языка и речи.

Нейроэкономика: нейробиология принятия решений

2011 · ARTICLE · ru

Происходящий в настоящее время синтез экономических наук, психологии и нейробиологии в рамках новой дисциплины – нейроэкономики, а также развитие новейших нейроимиджинговых методов обещают появление новой междисциплинарной модели, объясняющей механизмы принятия решений. Результаты нейроэкономических исследований демонстрируют, что принятие решений обусловлено работой относительно независимых нейрональных систем мозга, отобранных посредством естественного отбора. Взаимодействие «когнитивных» и «эмоциональных» нейрональных механизмов принятия решений определяет степень рациональности поведения человека.

No effects of mobile phone use on cortical auditory change-detection in children: an ERP study

2010 · ARTICLE · en

We investigated the effect of mobile phone use on the auditory sensory memory in children. Auditory event-related potentials (ERPs), P1, N2, mismatch negativity (MMN), and P3a, were recorded from 17 children, aged 11–12 years, in the recently developed multi-feature paradigm. This paradigm allows one to determine the neural change-detection profile consisting of several different types of acoustic changes. During the recording, an ordinary GSM (Global System for Mobile Communications) mobile phone emitting 902 MHz (pulsed at 217 Hz) electromagnetic field (EMF) was placed on the ear, over the left or right temporal area (SAR1g = 1.14 W/kg, SAR10g = 0.82 W/kg, peak value = 1.21 W/kg). The EMF was either on or off in a single-blind manner. We found that a short exposure (two 6 min blocks for each side) to mobile phone EMF has no statistically significant effects on the neural change-detection profile measured with the MMN. Furthermore, the multi-feature paradigm was shown to be well suited for studies of perception accuracy and sensory memory in children. However, it should be noted that the present study only had sufficient statistical power to detect a large effect size.